Answer:
The correct answer is a. MCl₃.
Explanation:
1. The given information states that the metallic element M reacts with oxygen to form an oxide with the formula M₂O₃.
2. The corresponding chloride of the metal will have a similar chemical formula, where the chlorine atoms replace the oxygen atoms.
3. In the oxide M₂O₃, the metal M has an oxidation state of +3.
4. To maintain the same oxidation state in the chloride, the formula of the corresponding chloride will be MCl₃, where the metal M has an oxidation state of +3 and is bonded to three chlorine atoms.
Therefore, the correct answer is a. MCl₃.